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C-reactive protein, serum/plasma concentration

Published: August 9, 2026Updated: August 16, 2026

This test measures the level of C-reactive protein in your blood. CRP is a protein produced by your liver in response to inflammation.

Quick summary

["CRP helps doctors assess inflammation in your body."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
52891-9
Short code
Cr Tiss-sCnt
Synonyms
Cr Tiss-sCnt
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

What Is C-Reactive Protein Used For?

CRP is commonly used to monitor conditions involving inflammation, such as infections, autoimmune diseases, or after surgery. It can also help track how well certain treatments are working.

Why Might Your Doctor Order This Test?

Your doctor may order CRP testing to check for signs of infection, inflammation, or to evaluate conditions like rheumatoid arthritis, lupus, or heart disease. It’s sometimes used as a screening tool before more invasive tests.

How Is This Test Performed?

A small blood sample is taken from a vein, usually in your arm. The blood is sent to a lab where it’s analyzed to measure CRP levels. Results are typically ready within a few days.

What Do My Results Mean?

Higher CRP levels may indicate inflammation or infection, while lower levels suggest less inflammation. However, individual results depend on your health status and medical history.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

CRP plays a key role in diagnosing and managing inflammatory conditions. Elevated levels can signal areas needing further investigation, such as infections, autoimmune disorders, or cardiovascular risks.

Short name

CRP

Frequently asked questions

What causes CRP levels to change?
CRP levels can rise due to infections (like pneumonia or urinary tract infections), injuries, surgeries, or certain medical conditions (like heart disease or arthritis). Stress, smoking, or certain medications may also affect CRP levels.
How often should I get this test?
Your doctor will determine how often you need CRP testing based on your health needs. Some people get it yearly, while others may need it more frequently if they have ongoing health concerns.
Can diet or lifestyle affect CRP levels?
Yes, diet, exercise, and weight management can influence CRP levels. Eating a heart-healthy diet, staying active, and maintaining a healthy weight may help lower inflammation.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy